Method for manufacture of 3-pentenoic acid ester

ABSTRACT

AN ESTER OF 3-PENTENOIC ACID IS PRODUCED BY ALLOWING BUTADIENE, CARBON MONOXIDE AND AN ALCOHOL TO REACT ING ISOQUINOLINE AS THE SOLVENT IN THE PRESENCE OF COBALT CARBONYL AS THE CATALYST. ISOQUINOLINE HAS LOW TOXICITY, A HIGH BOILING POINT AND A LOW SOLUBILITY WITH RESPECT TO PARAFFINS. THUS, IT PROVES TO BE A CONVENIENT SOLVENT IN THE DISTILLATION AND EXTRACTION TREATMENTS NEEDED FOR THE ISOLATION OF THE 3-PENTENOIC ACID ESTER FROM THE REACTION MIXTURE. THE CATALYST AND THE SOLVENT BOTH CAN BE USED CYCLICALLY IN THE PRESENT OPERATION.

United States Patent 3,778,466 METHOD FOR MANUFACTURE OF S-PENTENOIC ACID ESTER Akio Matsuda, Kashiwa, Japan, assignor to Agency of Industrial Science & Technology, Tokyo, Japan No Drawing. Filed Apr. 5, 1972, Ser. No. 241,452 Claims priority, appliczligignzlapan, June 18, 1971,

Int. Cl. C0 7c 69/54 US. Cl. 260-486 AC 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a method for the manufacture of 3-pentenoic acid esters from butadiene, carbon monoxide and alcohols. In the method of this invention, the catalyst and the solvent constitute important factors in the reaction involved. In a method conventionally known to the art it is claimed, for example, that a palladium complex or rhodium compound functions as an excellent catalyst and pyridine as an excellent solvent. However, there has not yet been developed a technique which permits this method to safely obtain the product in a high yield on a commercial scale.

In the reaction using a palladium complex as the catalyst and methanol as the solvent, the 3-pentenoic acid ester is obtained in a relatively low yield of about 60- 70% based on butadiene. Moreover, the palladium complex used therein is required to be in the form of a phosphine complex of palladium halogenide such as, for example, expensive (Bu P) PdCl Thus, this method has not so far developed to a commercializable level. In the method described in US. Pat. 3,161,672, there is used a rhodium catalyst. This method is not practicable in that rhodium is more expensive than cobalt and that the yield of pentenoic acid ester is at the most on the order of 50%. In another method of recent development, cobalt carbonyl is used as the catalyst and pyridine as the solvent respectively. Cobalt carbonyl is far less expensive than palladium or rhodium compounds and, therefore, proves more practical. Nevertheless, pyridine has high volatility and heavy toxicity. The separation of the product from pyridine is not easy to accomplish. This method, therefore, has a disadvantage in that separation must rely on precision distillation.

It is the main object of this invention to provide a method for manufacturing, safely and in an extremely high yield, a 3-pentenoic acid ester usable as a raw material for the production of an adipic ester which serves as a starting material for the production of polyesters, polyamides, and plasticizers. In addition, 3-pentenoic acid esters find a wide range of applications to the production of polymers. It is another object of this invention to provide a method suitable for commercial operation, wherein the solvent and the catalyst can be used cyclically.

To be specific, this invention relates to a method for manufacturing 3-pentenoic acid esters, which comprises allowing butadiene, carbon monoxide and alcohols to react in isoquinoline as the reaction solvent in the presence of cobalt carbonyl as the catalyst.

The present invention further relates to a method for the manufacture of a 3-pentenoic acid ester, which comprises subjecting the aforesaid reaction product to extraction with a paraffin thereby Obtaining an extracted phase containing the greater part of the produced 3-pentenoic acid ester and a minor fraction each of cobalt carbonyl and isoquinoline and a separated phase containing the greater part each of cobalt carbonyl and isoquinoline and a minor fraction of the produced 3-pentenoic acid ester, fractionally distilling the extracted phase to isolate 3-pentenoic acid ester therefrom, adding the separated phase together with a residue resulting from the distillation of the extracted phase and therefore containing therein cobalt carbonyl and isoquinoline to a new supply of reactants, and subjecting the resultant mixture to reaction, whereby the production of 3-pentenoic acid ester is continued while the catalyst and the solvent are put to use cyclically.

The present invention relates also to a method for the manufacture of a 3-pentenoic acid ester, wherein the aforesaid reaction product is subjected to vacuum distillation at a temperature below 50 C., for example, at normal room temperature to isolate the unaltered alcohol and the produced 3-penten0ic acid ester fractionally and, at the same time, obtain cobalt carbonyl and isoquinoline as the distillation residue, whereby the recovered cobalt carbonyl and isoquinoline will be used cyclically for the purpose of the reaction.

This invention relates to a method for the manufacture of a 3-pentenoic acid ester from carbon monoxide, an alcohol and butadiene by using cobalt carbonyl as the catalyst and isoquinoline as the solvent.

The alcohols usable for this manufacture include methanol, ethanol, propanol and butanol. The esters obtained as products are, therefore, the methyl ester, ethyl ester, propyl ester and butyl ester respectively of S-pentenoic acid. Of these products, the methyl ester finds the most useful application and, therefore, has particular importance from the industrial point of view.

The esters of 3-pentenoic acid are unsaturated esters and, therefore, are polymerizable. Thus, polymers can be obtained from these esters. The esters, upon reaction with carbon monoxide and alcohols, may be converted into adipic acid esters which are useful as starting materials for the production of polyesters, polyamides, plasticizers, etc.

As already mentioned, there has been suggested a method which has striking resemblance to the method of this invention. This method comprises allowing butadiene, carbon monoxide and an alcohol to react while using cobalt carbonyl as the catalyst and pyridine as the solvent. In the case of the reaction using pyridine, the yield of 3-pentenoic acid ester is with reference to butadiene. The reaction velocity in this case is equal to that which is obtained by the reaction of the present invention using isoquinoline as the solvent. Pyridine, however, has high toxicity and a low boiling point of C. Consequently, it is not easy to effect efiicient and economical separation of pyridine from the reaction mixture in which pyridine is present.

The method of the present invention excels the aforesaid method using pyridine as the solvent in that it provides improvements with respect to the drawback inevitably entailed by the use of pyridine. The inventors carried out a study and conducted experiments on various substances in search for a solvent which behaves better than pyridine. As a result, they have reached the conclusion that isoquinoline is most suitable for the purpose.

Isoquinoline is far less toxic than pyridine and has a higher boiling point of 240 C. Therefore, the separation of this solvent from the reaction mixture can be effected easily. What is more, the yield of 3-pentenoic acid ester based on butadiene is very high and favorably comparable with that obtained by using pyridine.

The solubility of isoquinoline with respect to parafiins such as cyclohexane and petroleum ether which are used as solvents for extraction is lower than that of pyridine.

By treating the reaction mixture as described below, the produced 3-pentenoic acid ester can be obtained and, at the same time, the solvent and the catalyst can be put to reuse without loss:

The unaltered alcohol and th'e produced 3-pentenoic Accordingly, the use of isoquinoline has an advantage 5 acid ester are fractionally distilled by subjecting the rethat h separation f thi l nt fr th produced action mixture to vacuum distillation at a temperature not S-pentenoic acid ester is accompilshed more easily. exceeding 50 C. As the residue of this distillation, there The 3-pentenoic acid ester may be satisfactorily sepais obtained dicobalt octacarbonyl in its undecomposed rated from the reaction mixture in a favorable yield on form together with isoquinoline. The catalyst and the a commercial scale by using any ordinary means. Particsolvent, when recovered, may be used again as raw mateularly by employing the procedure described below, the i l for h reaction, -P acid ester be Quail-led in a Yield 'Both isoquinoline and dicobalt octacarbonyl can be reefficlently On a commerclal scale Wlthout entallmg any covered in their entirety (100%) and put to reuse. Thus, 1055 of catalyst P this method proves highly advantageous from the com- F proqedlee esPec 1any slPtable for the Purposes of mercial point of view. As will be demonstrated in working this invention 1s described with respect to an example examples to be given hereafter, this method is very Prac 212333;??? riiii isiifg iifiiuiiirii 'llifififiiii in that it Produces absolutely no Wasteand dicobalt octacarbonyl as the catalyst and the produced In the Procedure memloned above catalyst methyl ester of S-pentenoic acid is separated from the may be any Cobalt iompolmd so long It produces resultant reaction mixture cobalt octacarbonyl 1n the course of reaction. In the start- First, an autoclave is charged with butadiene, methyl mg Feactants therefore the catalyst need not be limited alcohol, isoquinoline and dicobalt octacarbonyl. Under to dlcobalt octacawonylthe pressure of carbon monoxide gas, the contents of the The alcohols Whlch are usable for the Present Teactlon autoclave are heated and agitated. The relationship beinclude ethyl alcohol, p py 31601101 and butyl alcoholtween heating temperature, pressure and reaction time Th se alcohols are allowed to undergo reaction under used in this treatment is shown in the following table. practically the same conditions to produce ethyl ester,

Yield of 3-pentenoio acid ester Heating Converirom con- Concentration of catalyst temper- Reaction sion of vetted per butadiene (mol ature Pressure time butadiene butadiene percent) 0.) (atm.) (hr.) (percent) (percent) 120 200 3.5 91 82 140 300 2 92 85 120 300 1.5 92 92 140 300 3 s7 90 100 300 18 63 93 100 200 18 66 97 100 150 18 ea 94 100 100 18 4.5 95

From the preceding table, it is clear that the standard propyl ester and butyl ester respectively of 3-pentenoic reaction conditions are 120 to 140 C. of temperature and acid. 200 to 300 atmospheres of pressure. Where the reaction Stoichiometrically, butadiene and an alcohol react with temperature is low, for example, on the level of 100 0, each other at the ratio of 1 mol to 1 mol. Preferably, the the yield of 3-pentenoic acid ester from the converted alcohol may be used in an amount slightly in excess of butadiene is greater than where the reaction temperature this ratio to increase the conversion of butadiene. In the is higher. Yet, the reaction under these conditions must be reaction, butadiene partly underoges dimerization to give continued for as long as 18 hours to bring the converrise to about 10% of 4-vinyl-1-cyclohexene. sion of butadiene to the level of 60%. Thus, this reac- Now, the present invention is described with reference tion proves to be inefiicient. to working examples. This invention is not in any 'way After completion of the reaction, the reaction mixture limited to these examples. is removed from the autoclave and then treated as follows. EXAMPLE 1 This reaction mixture is subjected to extraction using a fli h as petroleum ether or cyclohexane The An autoclave made of stainless steel, having a capacity resultant extraction phase contains the greater part of the of about 300 and fitted with an agitator was charged produced methyl 3-penten0ate and a minor fraction each with P P butadiene of methanol, f isoquinoilne and dicobalt octacarbonyl, while the sepa mol of isoquinoline and 0.04 mol of dicobalt octacarbonyl rated Phase contains the greater part each f isoquinoline as the catalyst Under a pressure of 300 atmospheres of d di b octacarbonyl and a minor portion f the carbon monoxide, the contents of the autoclave were almethyl 3 pentenoate lowed to react at 120 C. for 1.5 hours, with an electro- From this extracted Phase the desired highly pure ester magnetic vertical agitator operated to stir the contents at of 3-pentenoic acid can be separated by distillation. The a rate of 80 vel'tlcal vlbratlons f Y extractant can also be recovered in a high Purity by there was obtained 88 g. of reaction mixture. When th s tillation. The recovered extractant may be put to reuse. reaction mlxture assayed by gas chromatography It The residue resulting from the distillation of the exwas found to comprise 43% of pioduced methyl tracted Phase is a black, viscous liquid. It contains a small gigizg i z gf 2 sg l i zi g z i i g gi S 23 1 of fil i z and g g octacarbmgl actor was passed through methanol cooled with dry ice w c as een pa 1a y ecompose an conse quei Y and then assayed by gas chromatography. Consequently, macnvatfad t the heat f at t tune of dlstlnatlonit was found that, 0.01 mol of the unaltered butadiene was Thus, thisresidue may be mixed with the separated phase remaining in the gaseous phase and used 111 the Subsequent cycle of redctiml- From the preceding results, it is seen that the conver- The dicobalt octacarbonyl deprived of activity is consion of butadiene was 92% and the yield of the methyl sequently reactivated to a reusable condition.

ester of 3-pentenoic acid based on butadiene was indicating that the selectivity of butadiene to the methyl ester of 3-pentenoic acid was 92%.

When the whole reaction mixture 'was subjected to extraction using 50 cc. of cyclohexane, it was divided into two layers, one on top of the other. The upper layer which was a cyclohexane phase weighing 72 g. comprised 67% of the formed methyl 3-pentenoate and a small fraction each of the used isoquinoline and dicobalt octacarbonyl. The lower layer which weighed 54 g. comprised 33% of the produced methyl 3-pentenoate and a major portion each of the used isoquinoline and dicobalt octacarbonyl.

When the upper layer was distilled, there were obtained 25 g. of highly pure methyl 3-pentenoate, 46 cc. of cyclohexane and 11 g. of distillation residue.

The distillation residue contained dicobalt octacarbonyl, isoquinoline and ester of 3-penten0ic acid.

Thorough recovery of both the catalyst and the solvent could be accomplished when 54 g. of the aforesaid lower layer resulting from the extraction was put together with 11 g. of the residue resulting from the distillation of the extracted phase and the resultant mixture was used as the catalyst-solution in the next cycle of reaction.

Analysis showed the catalyst-solution to contain 0.104 mol of the 3-pentenoic acid ester. Recovery of this ester could be effected by circulating the solution to the next cycle of reaction.

EXAMPLE 2 The same autoclave as described in Example 1 was charged 'with 0.389 mol of butadiene, 0.5 mol of methanol, and 65 g. of the catalyst-solution containing 0.104 mol of B-pentenoic acid ester recovered in Example 1. Under entirely the same conditions as used in Example 1, the con tents of the autoclave were allowed to react for the same length of time. Consequently, the conversion of butadiene was found to be 89%. The reaction mixture contained 0.422 mol of methyl S-pentenoate. This means that the actual output of the methyl ester of 3-pentenoic acid in this reaction was 0.318 mol, a value obtained by subtracting 0.104 mol (methyl ester already present in the catalystsolution) from the total 0.422 mol. The yield of the methyl ester of 3-pentenoic acid from butadiene was 82% and the yield (selectivity) of the ester with respect to the converted butadiene was 92% .When the reaction mixture was subjected to extraction using 100 cc. of petroleum ether, 83 of the formed methyl 3-pentenoate entered the upper layer (petroleum ether phase) and 17% of the ester remained in the lower layer. The major portion each of dicobalt octacarbonyl and isoquinoline was contained together with 17% of the methyl 3-pentenoate in the 46 g. lower layer. When the upper layer was distilled, it produced a petroleum ether fraction and a methyl S-pentenoate fraction while the portion of dicobalt octacarbonyl and isoquinoline which had entered the upper layer remained together with a part of methyl 3-pentenoate in the distillation residue weighing 23 g. The 46 g. of lower layer and the 23 g. of distillation residue 'were put together to obtain 69 g. of catalyst-solution to be used in the subsequent cycle of reaction. Analysis showed this catalyst-solution to contain 0.154 mol of methyl 3-pentenoate.

EXAMPLE 3 The same autoclave as described in Example 1 was charged with 0.380 mol of butadiene, 0.5 mol of methanol, and 69 g. of the catalyst-solution containing 0.154 mol of methyl 3-pentenoate recovered in Example 2. Under entirely the same conditions, the contents of the autoclave were subjected to reaction for the same length of time. The conversion of butadiene was found to be 74%. The reaction mixture contained 0.414 mol of methyl 3-pentenoate, indicating that the yield of the methyl ester in this reaction was 0.260 mol, a value obtained by subtracting 0.154 mol (methyl ester already present in the catalyst-solution) from the total 0.414 mol. The yield of the methyl ester from butadiene was 68% and the selectivity of the methyl ester with respect to butadiene was 92%. By following the same procedure as in Example 2, there was prepared a catalyst-solution to be used for the next cycle of reaction.

EXAMPLE 4 The same autoclave as described in Example 1 was charged with 0.389 mol of butadiene, 0.5 mol of ethanol,

' and the catalyst-solution recovered in Example 3. Under EXAMPLE 5 A solution containing 0.27 mol of methanol, 0.27 mol of isoquinoline and 0.016 mol of Co (C0) was introduced by a pump into an autoclave made of stainless steel, having a capacity of about 100 cc. and fitted with an agitator. Under the pressure of carbon monoxide, the contents of the autoclave was heated to 130 C. and 300 atmospheres. The agitator was set in motion and, at the same time, liquefied butadiene was introduced via the bottom of the reactor into the autoclave by a pump at a fixed rate of 0.054 mol/hr. The reaction was allowed to occur for three hours while the reaction conditions were maintained under constant conditions by the regulation of heater and the controlled feeding of carbon monoxide. At the end of three hours, the introduction of butadiene was discontinued and the reaction mixture was withdrawn through the base of the reactor and assayed for unaltered butadiene and the produced ester of S-pentenoic acid.

The conversion of butadiene was found to be 92%, the yield of the methyl ester of 3-pentenoic acid from the whole amount of butadiene introduced (0.162 mol) to be and the selectivity of the ester with respect to the converted butadiene to be 87%. When the reaction mixture was subjected to vacuum distillation at about 50 C., the produced methyl 3-pentenoate and the unaltered methanol were fractionally distilled. The dicobalt octacarbonyl and the isoquinoline were recovered in the form of distillation residue.

EXAMPLE 6 The distillation residue obtained in Example 5 was added to 0.27 mol of methanol. The mixture was introduced by a pump into the same device as described in Example 5. Under entirely the same conditions as used in Example 5, butadiene We fed at a rate of 0.055 mol/ hr. for three hours, to allow the contents of the device to undergo reaction.

Consequently, the conversion of butadiene was found to be 94%, the yield of methyl 3-pentenoate based on the whole amount of butadiene introduced to be 84%, and the selectivity of the ester with respect to the converted butadiene to be 89% respectively. The reaction mixture was subjected to vacuum distillation by the same procedure as in Example 5. Thus, the dicobalt octacarbonyl and isoquinoline were covered in the form of distillation residue.

EXAMPLE 7 The distillation residue obtained in Example 6 Was dissolved in 0.27 mol of methanol. The solution was introduced by a pump into the same device as described in Example 5. Under entirely the same conditions as used in Example 5, butadiene was introduced at a rate of 0.051 mol/hr. for three hours, to allow the contents of the device to undergo reaction.

Consequently, the conversion of butadiene was found to be 85%, the yield of the methyl ester of 3-pentenoic acid based on the whole amount of butadiene introduced to be 75%, and the selectivity of the ester with respect to the converted butadiene to be 88%.

I claim:

1. In a method for the manufacture of an ester of 3- pentenoic acid by reacting butadiene, carbon monoxide and an alcohol by using cobalt carbonyl as the catalyst in a. reaction solvent, the improvement which consists essentially of using isoquinoline as the reaction solvent.

2. The method according to claim 1 wherein the alcohol is a member of the group consisting of methanol, ethanol, propanol and butanol.

3. In a method for the manufacture of an ester of 3- pentenoic acid by reacting butadiene, carbon monoxide and an alcohol by using cobalt carbonyl as the catalyst in a reaction solvent, the improvement which consists essentially of using isoquinoline as the reaction solvent, subjecting the reaction product to extraction with parafiin and obtaining an extracted phase containing the greater part of the ester of 3-pentenoic acid and a minor portion each of isoquinoline and cobalt carbonyl and obtaining a separated phase containing the greater part each of isoquinoline and cobalt carbonyl and a minor portion of the ester of 3-pentenoic acid, distilling the extracted phase to separate the paraflin fraction, 3-pentenoic acid ester fraction as a product and a black viscous residue, using the separated paraffin fraction for the extraction of the reaction product, and using the said black viscous residue together with the separated phase as the raw material for the initial reacting step.

4. In a method for the manufacture of an ester of 3- pentenoic acid by reacting butadiene, carbon monoxide and an alcohol by using cobalt carbonyl as the catalyst in a reaction solvent, the improvement which consists essentially of using isoquinoline as the reaction solvent, subjecting the reaction product to vacuum distillation at a temperature not exceeding about C. thereby obtaining the produced ester of 3-pentenoic acid as a distillation fraction together with a distillation residue composed of isoquinoline and cobalt carbonyl, and using this residue as the raw material for the reaction step.

References Cited UNITED STATES PATENTS 2/1952 Hyson 260533 A 1/1958 Hasek 260-49 FC OTHER REFERENCES Du-pont et al.: Bull. Soc. Chim (France), 15, 929-32 (1948).

US. Cl. X.R. 260666 B 

